1. Field of the Invention
The subject invention relates to a passively activated safety shield for a needle, such as the needle for a fluid collection tube holder.
2. Description of the Related Art
A prior art blood collection set or IV infusion set includes a needle cannula having a proximal end, a pointed distal end and a lumen extending between the ends. The proximal end of the needle cannula is securely mounted in a plastic hub with a central passage that communicates with the lumen through the needle cannula. Thin flexible thermoplastic tubing is connected to the hub and communicates with the lumen of the needle cannula. The end of the tubing remote from the needle cannula may include a fixture for connecting the needle cannula to a blood collection tube or some other receptacle. The specific construction of the fixture will depend upon the characteristics of the receptacle to which the fixture will be connected.
Some fluid collection procedures employ a rigid blood collection holder instead of the above-described blood collection set. The tube holder includes a proximal end, a distal end and a tubular side wall extending between the ends. The proximal end of the holder is widely open and defines an entrance to a tube receptacle within the tubular side wall. A distal end wall extends partly across the distal end of the holder and has a mounting aperture that communicates with the tube receptacle. The mounting aperture in the distal end wall may include internal threads, movable jaws or similar structure for releasably receiving a needle assembly. The needle assembly includes a rigid plastic hub configured for releasable engagement with structure at the mounting aperture in the distal end wall of the holder. The needle assembly further includes a non-patient cannula that extends proximally from the hub and an IV cannula that extends distally from the hub. The non-patient cannula typically is covered by an elastomeric multiple sample sleeve and projects into the receptacle of the holder when the hub of the needle assembly is engaged with the threads or other structure at the mounting aperture in the distal end wall of the tube holder. The proximally extending non-patient cannula and the distally extending IV cannula typically are covered by separate packaging covers prior to use.
The needle assembly, tube holder and evacuated tube are employed by first removing the packaging cover over the non-patient cannula and engaging the hub in the mounting aperture in the distal end wall of the tube holder. Thus, the non-patient cannula projects into the holder. The packaging shield over the IV cannula then is removed and the pointed distal end of the IV cannula is used to access a blood vessel or other source of bodily fluid to be tested. The evacuated tube then is urged into the open proximal end of the holder so that the non-patient cannula pierces the rubber closure of the evacuated tube. The pressure differential will cause blood or other bodily fluid to flow into the evacuated tube. The evacuated tube will be separated from the needle holder after sufficient blood or other bodily fluid has been collected. Additional evacuated tubes then can be inserted into the holder for collecting further samples. The IV cannula is withdrawn from the patient after a sufficient number of samples have been collected.
Accidental sticks with a needle are painful and can lead to infection. Additionally, an accidental stick with a used needle can transmit disease. Accordingly, most prior art needle assemblies are provided with some form of shield to minimize the risk of an accidental needle stick. For example, prior art needle assemblies typically are provided with a packaging cover mounted over the needle cannula prior to use. The prior art packaging cover is frictionally engaged with the needle hub and can be removed immediately prior to using the needle assembly. Reshielding the used needle cannula with the original packaging cover would require the medical practitioner to hold the needle assembly in one hand and to move the point of the used needle cannula toward the hand in which the packaging cover is held. This reshielding procedure can lead to the accidental needle stick that the medical practitioner is trying to avoid. Accordingly, manufacturers of needle assemblies discourage medical practitioners from reshielding the used needle cannula with the original packaging cover.
Most prior art needle assemblies include a safety shield that can be moved into shielding engagement with a used needle cannula without risking an accidental needle stick. For example, some prior art needle assemblies include a needle shield hingedly connected to the needle hub. The hinged shield initially may be in a position that is spaced angularly from the needle cannula. However, the shield can be rotated relative to the needle hub and into shielding engagement around the used needle cannula. Digital forces for rotating this prior art hinged safety shield typically can be applied at a location near the needle hub and spaced from the pointed end of the needle cannula. As a result, shielding can be carried out manually without placing a hand near the point of the used needle cannula.
Other prior art safety shields include a rigid tubular member that is telescoped over the needle hub and/or over any medical device to which the needle assembly is mounted. The rigid safety shield can be moved from a proximal position where the needle cannula is exposed, into a distal position where the safety shield surrounds the used needle cannula. This shielding operation typically can be completed without placing a hand near the tip of the used needle cannula.
Some needle shields are referred to as tip guards, and include a small rigid guard that can be telescoped along the length of a needle cannula. The prior art tip guard may include some form of tether for limiting the travel of the tip guard to the length of the needle cannula. Additionally, the prior art tip guard typically includes structure that lockingly engages over the tip of the used needle cannula to prevent a re-exposure. The structure for preventing re-exposure may include a metallic spring clip or a transverse wall integrally formed with one end of the tip guard.
Some prior art needle assemblies are provided with metallic coil springs between the needle hub and the safety shield. A latch typically is provided for retaining the spring in a compressed state prior to and during use of the needle cannula. The latch is released upon removal of the needle cannula from the patient, and the spring then drives the shield distally and into shielding engagement with the needle cannula. Needle cannulas for blood collection sets and IV infusion sets typically are very small. Accordingly, the latches and the springs also must be very small. As a result, it often is difficult to access and release the latch. Furthermore, there is a significant potential for unreliable performance of the very small coil spring that had been stored in a compressed state for a long time.
All of the above described prior art shields for used needle cannulas require direct manual activation by the medical practitioner. The practitioner, however, often has many simultaneous responsibilities in the hectic environment of a health care facility. Thus, the used needle cannula may be withdrawn from a patient and deposited on a nearby surface with the intention of completing the shielding at a more convenient time. However, the exposed used needle cannula creates a substantial risk prior to completion of the shielding. Furthermore, there are many occasions where the needle of a blood collection set or an IV infusion set is pulled out, intentionally or unintentionally, by a patient. In this situation, shielding will not have been attempted, and the used needle cannula will remain exposed. In still other instances, the medical practitioner will inadvertently drop the used needle cannula immediately after withdrawal from the patient or during a shielding attempt. The immediate reaction of many medical practitioners will be to reach quickly for the falling needle cannula. This attempt to retrieve the falling needle cannula creates a significant possibility for an accidental needle stick.
Efforts have been made to develop a completely passive shielding assembly for use with a fluid collection tube holder, such as the holder for receiving an evacuated tube during a blood collection procedure. Some such devices include complex arrangements of springs and latches.
In view of the above, it is an object of the subject invention to provide a passively shieldable needle assembly that will reliably achieve secure shielding of a used needle cannula automatically upon removal of the needle cannula from the patient and without requiring special manipulation by a user.
One aspect of the invention is directed to a passively shieldable needle set. The needle set includes a needle cannula having a proximal end, a pointed distal end and a lumen extending between the ends. The needle set further comprises a hub having a proximal end, a distal end and a passage extending between the ends. The proximal end of the needle cannula is securely mounted in the passage of the hub. Flexible tubing may be mounted to the proximal end of the hub such that the passage through the tubing communicates with the lumen of the needle cannula. A fixture may be mounted to the end of the tubing remote from the hub. The fixture enables the needle cannula and the tubing to be placed in communication with an appropriate receptacle, such as a blood collection tube.
The needle set further includes a passive shield assembly. The shield assembly includes a tip guard that is telescoped on the needle cannula for sliding movement from a proximal position where the tip guard is substantially adjacent the hub to a distal position where the tip guard surrounds the pointed distal end of the needle cannula. Additionally, the tip guard may be configured to prevent a return proximal movement after the tip guard has advanced sufficiently in a distal direction to protectively enclose the distal tip of the needle cannula.
The tip guard may comprise a housing and a protective clip, each of which is formed from a material that is sufficiently hard and rigid to prevent piercing by the distal tip of the needle cannula. The housing may be formed from a thermoplastic material, and the clip may be formed from a metallic material. The clip is configured to be biased against the needle cannula as the tip guard moves from its proximal position toward the distal position. However, the clip is further configured to move over the tip of the needle cannula when the tip guard is in its distal position.
The passive shield assembly further includes a pair of resiliently deflectable leaves. The leaves have proximal ends that are connected to opposite respective sides of the hub. The leaves further have distal ends connected to opposite sides of the tip guard. A portion of each leaf between the ends is resiliently collapsible onto itself and into close overlying relationship to the needle hub. Thus, the collapsed leaves can be gripped manually by the medical practitioner to manipulate the needle assembly prior to and during veinipuncture. However, a release of forces on the collapsed leaves enables the leaves to resiliently move toward an undeflected condition in which the leaves extend substantially linearly and parallel to one another on opposed sides of the needle cannula. This resilient unfolding of the leaves transports the tip guard distally along the needle cannula. The leaves have lengths sufficient to enable the tip guard to move into shielding engagement with the tip of the needle cannula, without moving distally beyond the needle cannula.
The needle set further includes a packaging cover having an open proximal end, a distal end and a generally tubular sidewall extending therebetween. Portions of the sidewall of the packaging cover adjacent the open proximal end are configured to be mounted frictionally over the hub and over the collapsed leaves. Thus, the packaging cover functions to hold the leaves in their collapsed condition. The sidewall of the packaging cover is sufficiently long to cover the needle cannula when the proximal end of the packaging cover is mounted to the hub.
A medical practitioner employs the needle set of the subject invention by gripping the collapsed leaves of the shield assembly between a thumb and forefinger at a location proximally of the packaging cover. The packaging cover then is removed, and the tip of the needle cannula is inserted into a blood vessel of a patient. Upon completion of the insertion, the medical practitioner releases the grip on the collapsed leaves, and the leaves begin to unfold due to their inherent resiliency. The unfolding of the leaves causes the tip guard to move distally along the needle cannula. The distal movement of the tip guard will terminate when the tip guard contacts the skin of the patient. After completion of the medical procedure, the practitioner grabs the needle hub with a thumb and forefinger and pulls the needle cannula from the patient. This relative proximal movement of the needle cannula permits the leaves to unfold further, thereby moving the tip guard into surrounding relationship to the tip of the needle cannula. The clip or other such structure within the tip guard prevents a re-exposure of the used needle cannula.
It will be appreciated that the shield assembly is triggered by the medical practitioner, but shielding is entirely passive and automatic after the triggering. The triggering action is the release of the collapsed leaves by the medical practitioner. This release can occur after the needle cannula has been placed properly in a blood vessel. Alternatively, this triggering can occur if the needle set is inadvertently dropped. The elapsed time for this shielding will vary depending upon the characteristics of the leaves. Typically, however, complete shielding can occur before a dropped needle has fallen one foot.
Another aspect of the invention relates to a passively shieldable needle assembly. The needle assembly includes a needle cannula having a pointed proximal end, a pointed distal end and a lumen extending between the ends. The needle assembly further comprises a hub having a proximal end, a distal end and a passage extending between the ends. Portions of the needle cannula between the pointed proximal and distal ends are mounted securely in the passage of the hub. Thus, the pointed proximal end of the needle cannula projects proximally beyond the hub and the pointed distal end of the needle cannula projects distally beyond the hub. External surface regions of the hub near the proximal end of the hub may be formed with mounting structures, such as an array of external threads, at least one annular groove or at least one annular rib. The mounting structure enables the needle hub to be secured to a tube holder that is configured to slidably receive an evacuated fluid collection tube. The needle assembly may further include a multiple sample sleeve mounted over the proximal portions of the needle cannula and secured to the proximal end of the hub. The proximal portions of the needle cannula and the multiple sample sleeve project into the tube holder when the hub of the needle assembly is mounted to the holder.
The needle assembly further includes a passive shield assembly and a packaging cover substantially as described with respect to the first embodiment. However, the resiliently deflectable leaves of the passive shield assembly preferably are configured to project into partly overlying relationship with the tube holder when the needle assembly is mounted to the holder. Thus, portions of the collapsed leaves can be gripped manually by the medical practitioner simultaneously while gripping the tube holder for drawing blood or other bodily fluid from a patient. The packaging cover may be a distal packaging cover for covering the distal projection of the needle cannula beyond the hub and for holding the leaves in their collapsed condition. The needle assembly may further include a proximal packaging cover for covering the proximal projection of the needle cannula beyond the hub.
The needle assembly is employed by first removing the proximal packaging cover from the needle assembly and attaching the needle assembly to a tube holder. In this condition, portions of the collapsed leaves or extensions of the leaves are disposed on opposite sides of the holder. The medical practitioner grips these portions of the leaves that overlie the tube holder for securely gripping both the collapsed leaves and the holder. The distal packaging cover then is removed and the exposed distal point of the needle cannula is employed in a conventional manner to access a blood vessel. Immediately upon accessing the blood vessel, the medical practitioner shifts his or her grip on the tube holder so that the collapsed leaves are released. The leaves then begin to unfold due to their inherent resiliently, substantially as in the first embodiment. This unfolding of the leaves causes the tip guard to move distally along the needle cannula and into gentle contact with the skin of the patient. The medical practitioner then inserts an evacuated tube into the open proximal end of the tube holder so that the evacuated tube is urged into communication with the proximal end of the needle cannula. The pressure differential will generate a flow of blood into the evacuated tube. The evacuated tube is withdrawn from the holder after a sufficient volume of fluid has been collected, and one or more evacuated tubes may be inserted successively into the holder for drawing additional samples. After the last sample has been collected, the tube is withdrawn from the holder and the holder is pulled away from the patient. As a result, the leaves will unfold further and move the tip guard into surrounding relationship with the tip of the needle cannula as in the first embodiment.
Passive activation of the shield assembly can be triggered by insertion of a fluid collection tube into the tube holder to which the needle assembly is mounted. For example, the tube holder may include an actuator opening in the distal end wall of the tube holder at a location offset from the needle cannula. An actuator arm may be mounted or formed near the tip guard and may project proximally from the tip guard into and through the actuator opening of the tube holder when the tip guard is in its proximal position. The actuator arm may be formed with a locking structure that releasably engages a portion of the tube holder when the tip guard is in the proximal position. The actuator arm is disposed to be contacted by a fluid collection tube as the tube is inserted into the tube holder. Distal movement of the tube into the tube holder will disengage the locking structure on the actuator arm from the tube holder and will initiate the distal movement of the tip guard along the cannula. The leaves will resiliently unfold as in the prior embodiments, thereby propelling the tip guard initially into contact with the skin of the patient, and eventually into shielding relationship with respect to the pointed distal end of the needle cannula. As in the previous embodiments, the resilient leaves will unfold into a position where the leaves lie on opposite sides of the used needle cannula, and hence will prevent inadvertent contact with the needle cannula. Furthermore, the actuator arm will parallel the needle cannula and will further prevent inadvertent contact with the used needle cannula. As in other embodiments, the expanded leaves will prevent the tip guard from moving distally beyond the distal tip of the needle cannula.